PWD_MKDB(8) BSD System Manager's Manual PWD_MKDB(8)NAMEpwd_mkdb - generate the password databases
SYNOPSISpwd_mkdb [-dlpr] [-c cachesize] file
DESCRIPTION
Pwd_mkdb creates db(3) style secure and insecure databases for the speci-
fied file. These databases are then installed into /etc/spwd.db and
/etc/pwd.db respectively. The file is installed into /etc/master.passwd.
The file must be in the correct format (see passwd(5)). It is important
to note that the format used in this system is different from the his-
toric Version 7 style format.
The options are as follows:
-c cachesize
Set the cache size of the database routines to cachesize kilobytes.
-d Causes pwd_mkdb to write all output files in the current working
directory (e.g., /etc/passwd becomes ./passwd). This can be used to
build a pwd.db file for an anonymous ftp directory. You should not
run as root when doing this, because if you accidentally forget the
-d option, pwd_mkdb could overwrite your /etc/master.passwd file.
When creating the databases for an anonymous ftp directory be sure
that you do not install the spwd.db or master.passwd files; they
are not needed for anonymous ftp and they contain the encrypted
passwords, which you do not want to make available.
-l Do not try to rename file to /etc/master.passwd (or
./master.passwd).
-p Create a Version 7 style password file and install it into
/etc/passwd.
-r Do not fail if root is unusual (wrong uid, etc).
The two databases differ in that the secure version contains the user's
encrypted password and the insecure version has an asterisk (``*'').
The databases are used by the C library password routines (see
getpwent(3)).
The -c option is provided for performance tuning. The default parameter
(2048K) should provide reasonable performance on databases with 6000 or
fewer accounts. Increasing the cache size can be of great benefit on
files with large numbers of entries, but too much cache can cause the ma-
chine to start paging and reduce performance.
Pwd_mkdb exits zero on success, non-zero on failure.
FILES
/etc/master.passwd The current password file.
/etc/passwd A Version 7 format password file.
/etc/pwd.db The insecure password database file.
/etc/pwd.db.tmp A temporary file.
/etc/spwd.db The secure password database file.
/etc/spwd.db.tmp A temporary file.
BUGS
Because of the necessity for atomic update of the password files,
pwd_mkdb uses rename(2) to install them. This, however, requires that
the file specified on the command line live on the same file system as
the ``/etc'' directory. For the same reason, the temporary output files
must also reside on the same file system as the final files. Thus, you
must have enough free space for both the old and new files.
There are the obvious races with multiple people running pwd_mkdb on dif-
ferent password files at the same time. The front-ends to pwd_mkdb:
chpass(1), passwd(1) and vipw(8), handle the locking necessary to avoid
this problem.
The file /etc/master.passwd is always used for locking even if the -d op-
tion is specified. This effectively prevents any user other than the su-
per user from running pwd_mkdb. While it might seem logical to lock on
file this does not work when two updates in the same directory are at-
tempted at the same time from different files. For example:
# (cd /etc ; pwd_mkdb-pd /etc/master.passwd) &
# (cd /etc ; pwd_mkdb-pd /tmp/master.new) &
In this case there will be collisions on all the files created.
COMPATIBILITY
Previous versions of the system had a program similar to pwd_mkdb,
mkpasswd(8), which built dbm(3) style databases for the password file
but depended on the calling programs to install them. The program was
renamed in order that previous users of the program not be surprised by
the changes in functionality.
SEE ALSOchpass(1), passwd(1), db(3), getpwent(3), passwd(5), vipw(8)BSDI BSD/OS April 27, 1995 2